The present invention relates to an image forming system and image forming method, and particularly to an image forming system having a plurality of stackers for stacking paper after image formation and an image forming method.
Image forming systems are known in which images are formed on a plurality of papers and then the plurality of papers are separated and stacked with every prescribed numbers of sheets. This type of image forming system comprises an image forming mechanism for recording images on paper and a stacking unit for separating the paper transported from the image forming mechanism into stacks of the prescribed number of sheets.
Patent document 1 discloses technology wherein a plurality of bin modules are used as the stacking unit and sheet material, which is the paper on which recording, has been done is stacked. According to this technology, the sheet materials on which recording has been done are stacked in a particular bin module, and when the number of sheet materials reaches the maximum sheet number for stacking in this module, a switch is made to another bin module and stacking is continued.
[Patent document 1: Japanese Patent Application Laid-Open No. HEI10-152260 publication]
In the technology described in Patent document 1, the sheet materials are stacked in one bin module until the maximum sheet number per stack is reached, but as a result, when an image forming job in which recording is done for large numbers of sheet or when a large copy set is done, even if the recorded sheet materials are for the same image forming job or copy set, recording may span more than one modules and the sheet materials are separated. Thus when book making or the like is being done, after separation of the sheet materials, in many cases the complicated operation of checking each page becomes necessary.
The present invention was conceived in view of the above described situation and an object thereof is to provide an image forming system in which even when an image forming job or copy set in which large volume image formation is performed, it is possible to ensure that paper for the image forming job unit or copy set unit are stacked in the same stacking unit, and an image forming method using this image forming system.